TITLE: Hydrogrossular NMNH120555 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH120555

MINERAL_TYPE: Nesosilicate

MINERAL: Hydrogrossular (Garnet group)

FORMULA: Ca3Al2(SiO4)3-x(OH)4x

FORMULA_HTML: Ca3Al2(SiO4)3-x(OH)4x

COLLECTION_LOCALITY: Rustenberg, South Africa

ORIGINAL_DONOR: National Museum of Natural History

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscpy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Grossular.

Sample was sieved to the grain size interval <250µm.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: hydrg120.out, *.mdi (smear mount on quartz plate)
References: Borg and Smith (1969), JCPDS #10-288, DHZ, v. 1a (1982), Huebner's reference patterns
Found: Garnet; unidentified moderate to weak reflections at 6.0, 4.0, 3.58, 3.23, 3.17, 2.75, 2.59. and 1.76 anstroms.
Sought but not found: anorthite, Fe-oxyhydroxides, ilmenite, apophyllite, prehnite, thaumasite, gehlenite, xonotlite.

Comment: The garnet unit cell dimension ranges more or less continuously from 11.95 to 11.89 angstroms, consistent with grossular-rich members of the grossular-hydrogrossular series. Optically the material consists of colorless, weakly anisotropic garnet and about 10% brownish weakly anisotropic garnet charged with opaque and a few bright red (hematite?)inclusions

J.S. Huebner, J. Pickrell, and T. Schaefer, 1994, written communication.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EM(WDS) # XRF, EM(WDS), ICP(Trace), WChem


COMPOSITION: SiO2 31.44 wt% SiO2
COMPOSITION: TiO2 0.04 wt% TiO2
COMPOSITION: Al2O3 21.40 wt% Al2O3
COMPOSITION: Cr2O3 0.00 wt% Cr2O3
COMPOSITION: V2O3 0.00 wt% V2O3
COMPOSITION: FeO 0.46 wt% FeO
COMPOSITION: NiO 0.00 wt% NiO
COMPOSITION: MnO 0.89 wt% MnO
COMPOSITION: MgO 0.17 wt% MgO
COMPOSITION: CaO 36.14 wt% CaO
COMPOSITION: Total 90.54 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total wt%

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

EM analysis by Gregg A. Swayze at the USGS Branch of Geophysics, Denver.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 2229 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=